The present invention relates to a soot blaster.
Soot blasters are used to blast sooty deposits off hot surfaces, especially off heating surfaces of boilers and the like. They use a tube-shaped lance having one or more outlet nozzles through which a gaseous and/or liquid blasting medium is expelled at high velocity. The lance is turningly inserted into the space to be cleaned, advanced to its leading end position and is then retracted again.
It is customary that the tip of the lance is provided with two opposite nozzles. If so, these perform during the cleaning operation a double-helix movement, the spacing of the helices being equal to half of the selected forward movement per rotation of the lance. The drive elements for the longitudinal and rotary movement during each cleaning incident will always be the same. That is to say that the fluid blasts invariably contact the same areas of the surface being cleaned, which eventually leads to erosion damage to these surfaces.
To avoid this, it is known from German Pat. No. 2,757,981 to so construct the soot blaster that each cleaning incident is begun with the nozzles in a different position. This construction proposes to use two free-wheeling devices between the drive shaft for the longitudinal drive and the drive for the rotary motion. These devices are actuatable in mutually opposite directions and one of them has a predetermined play built into it in direction of rotation of the drive shaft.